Conventionally, most containers have a main body structure and a door is disposed at the rear end thereof to upload and unload cargos. However, the inner receiving space of conventional containers is usually fixed and cannot be expanded, so the transportation costs cannot be easily reduced. Furthermore, the containers can be used for other purposes, but the restricted inner space is still a concern under such circumstances. Therefore, there remains a need for a new and improved container structure to overcome the problems discussed above.